Delivering therapeutic agents in vivo to a precise location using steerable entities is highly desirable in medical practice. Using magneto-responsive self-propelled entities as carriers (nano-robots or magnetotactic bacteria carriers) and direction-setting magnetic fields for carrying loads such as therapeutic agents (including radioisotopes) or diagnostic (including imaging) agents in narrowing blood vessels (such as capillaries) or in far reaching regions (e.g. the interstitial region of a tumor) is difficult, especially when operating deeper in the body to induce a propulsion (pulling) force on the carriers due to the small size of the entities (e.g. magnetic carriers) and technological limits. As such, carriers or magneto-responsive entities referred to here as Steerable Self-Propelled Entities (SSPE) are being considered to alleviate such limitations.
In a co-assigned patent by Martel et al (U.S. Pat. No. 7,962,194), ferromagnetic particles are shown to be controllably propelled by an magnetic resonance imaging (MRI) system within a patient. Martel (US Patent Application Pre-Grant Publication US2006/0073540) also teaches the directional control of micro-objects using magnetotactic bacteria in two dimensional space, such as in a petri dish. Such bacteria are self-propelled and naturally swim in the direction of the magnetic field. One of the drawbacks of the US2006/0073540 prior art is that it cannot be used to efficiently target objects in 3 dimensions, such as in large blood vessels, organs or tissues of the human body.
There is a need to increase targeting efficacy and dosage of therapeutic agents being delivered to targets in the body, while being potentially visible (detectable) with imaging modalities such as MRI. To achieve this, an aggregate of SSPEs is necessary. As such, an apparatus or system with related methods capable of aggregating SSPEs and controlling their displacement is highly desirable.